Articles (referred to simply as “components” below) having a three-dimensional shape, such as parts and units that construct commodities and products are designed conventionally using three-dimensional CAD (3D-CAD). When designing is performed using 3D-CAD, a 3D model of the component is fabricated and attribute information such as dimensions, dimensional tolerance, geometrical tolerance, remarks and symbols are input with respect to the 3D model. This attribute information is attached to the 3D model or to elements such as surfaces, edge lines or apices of the 3D model.
The 3D model and attribute information constitute information that is necessary for component machining, inspection, assembly or maintenance and must be conveyed in easily understandable fashion, efficiently and without mistakes from the operator (designer) who makes the input to the operator (machining, manufacture or inspection technician, etc.) who observes it.
With the objective of fabricating a component efficiently by appending attribute information to a 3D model efficiently with good operability and viewability and utilizing the appended attribute information efficiently to exploit the 3D model and attribute information in the fabrication of the component, the applicant has already proposed an information processing apparatus for setting virtual planes with which attribute information has been associated and storing attribute information in association with the virtual planes (see Prior Art 1: the specification of Japanese Patent Application Laid-Open No. 2002-324086).
With such 3D-CAD, there are many opportunities to select surfaces when creating a 3D model and inputting attribute information to the 3D model. More specifically, selection of surfaces is sought in various operations, such as when performing modeling in a direction parallel or orthogonal to the surface of a 3D model, when coloring a surface of a 3D model, when checking the distance or angle between one surface and another surface of a 3D model, and when inputting dimensions or remarks to the surface of a 3D model. A general method of selecting a surface is to display on a screen the surface that is desired to be selected and then click this surface using a pointing device such as a mouse.
An operation through which a distance dimension, which is attribute information, is input using the above-described surface selecting method will now be illustrated. FIG. 14 is a flowchart illustrating the processing of an operation for inputting a distance dimension according to the prior art. This represents an operation for inputting a distance dimension with regard to two surfaces A and B of a 3D model (see FIGS. 3 and 4). The state of the 3D-CAD display when input of a dimension has started is as illustrated in FIG. 3. The operation for inputting a distance dimension is performed in the following sequence: activate a command that is for inputting the distance dimension; select a first surface; select a second surface; specify the associated attribute layout plane; decide the dimension position; and deactivate the command that is for inputting the distance dimension.
More specifically, first a command for creating a distance dimension is activated from an attribute information creating menu (step S101) and a first surface A is selected. That is, it is determined whether the surface to be selected is being displayed (step S102). If it is not being displayed, then the attitude of the 3D model is changed to display the surface to be selected (step S104) and the surface to be selected is clicked (step S103). If the surface is being displayed, on the other hand, then the surface to be selected is clicked as is. Since surface A is being displayed in FIG. 3, this surface is selected by being clicked at step S103. When the surface A is selected, it is highlighted until completion of the dimension input in such a manner that the surface whose dimension is being input will be easy for the operator to discern (see FIG. 6).
Next, the second surface B is selected. The second surface B is selected in a manner similar to that of the first surface A. That is, it is determined whether the surface to be selected is being displayed (step S105). If it is not being displayed, then the attitude of the 3D model is changed to display the surface to be selected (step S107) and the surface to be selected is clicked (step S106). If the surface is being displayed, on the other hand, then the surface to be selected is clicked as is. Since the state of the display in this case is as shown in FIG. 6, surface B is not being displayed because it is hidden by other parts of the 3D model. This means that surface B cannot be selected by clicking it as is. Accordingly, the displayed attitude of the 3D model is changed at step S107 so as to display surface B. Surface B being displayed is then selected by being clicked at step S106. FIG. 15 is a diagram illustrating a state in which surface B is displayed. If surface B is selected, a dimension 2a is displayed (see FIG. 16). At this point in time, however, position has not been finalized and the position will change by following up movement of a mouse cursor 5. Further, surfaces A and B whose dimensions are being input are highlighted at this time. FIG. 16 is a diagram illustrating a state in which a dimension is displayed.
The operator thenceforth specifies an attribute layout plane 2 that correlates the dimension 2a (step S108). By specifying the attribute layout plane, it becomes possible for the distance dimension 2a to be placed in the attribute layout plane 2. By moving the cursor 5 under these conditions, the dimension 2a is moved in the attribute layout plane 2 (see FIG. 17). In comparison with the state that prevails at step S106, the dimension position moved is limited to the attribute layout plane 2. FIG. 17 is a diagram illustrating the state in which the position of the distance dimension is limited to the attribute layout plane 2. The position of the distance dimension 2a is decided by clicking a desired position in the attribute layout plane 2 (step S109; see FIG. 18). When this operation is completed, the highlighted surfaces A and B are restored to their usual state. FIG. 18 is a diagram illustrating a state in which the position of the distance dimension has been decided. Finally, the command for creating this distance dimension is terminated by clicking a dimension-input completion button (not shown) (step S110). A surface selection operation is performed and a dimension is input to the 3D model through this procedure.
Another general method of selecting a surface has also been put into practice. According to this method, any position on a display is clicked when a surface is to be selected. When the position is clicked, surfaces that overlap in the line-of-sight direction of the display with respect to the clicked position are highlighted one after another from the front side and a surface deciding operation is performed when the desired surface is in the highlighted state, whereby selection of the desired surface is achieved. An operation for inputting the distance dimension 2a (attribute information) between two surfaces A and B will be described with regard to a 3D model (see FIGS. 3 and 4) in a manner similar to that of the prior art set forth above.
FIG. 19 is a flowchart illustrating the processing of an operation for inputting a distance dimension according to another example of the prior art. The state of the 3D-CAD display when this dimension is input is that shown in FIG. 3, which is similar to the example of the prior art described above. The operation for inputting the distance dimension is performed in the following sequence: activate a command to input the distance dimension; select a first surface; select a second surface; specify the associated attribute layout plane; decide the dimension position; and deactivate the command to input the distance dimension.
Processing identical with that of the example of the prior art set forth above is identified by the same step numbers and need not be described again in detail. When the first surface A is to be selected, the surface A is being displayed (see FIG. 3) and therefore it is selected by being clicked. Further, when the surface A is selected, it is highlighted until the input of dimension is completed. This also is similar to the example of the prior art described above.
Next, when the second surface B is to be selected, the display is in the state shown in FIG. 6 and therefore the surface B is not being displayed because it is hidden by other parts of the 3D model. This means that surface B cannot be selected by clicking it. In this case, a surface search button (not shown) is clicked to thereby establish a surface selection mode (step S107A) and a position that is superimposed on the desired surface B is clicked (step S107B; see FIG. 20). Assume that the position of cursor 5 shown in FIG. 20 has been clicked. FIG. 20 is a diagram illustrating the state of the display in the surface selection mode. FIGS. 21A, 21B, 22A and 22B are diagrams showing the procedure of the surface selecting operation. By virtue of this operation, first a surface E, which is the frontmost surface among the surfaces that overlap the clicked position, is highlighted, as illustrated in FIG. 21A. An operation window 200 is displayed at the same time. FIG. 23 is a diagram illustrating the operation window 200.
If a “NEXT” button 201 in the operation window 200 is clicked, a surface F farther back than the surface E is highlighted (step S107C), as illustrated in FIG. 21B. If the “NEXT” button 201 is clicked again and again, a surface G (see FIG. 22A) and the surface B (see FIG. 22B) are highlighted one after the other in order from the front side. If there are no further surfaces in back (in this case, surface B is the surface farthest back), the surface highlighted returns to the frontmost surface (surface E in this case). If a “BACK” button 203 is clicked, surfaces will be highlighted in reverse order starting from the surface farthest back. The desired surface B is highlighted as a result of this operation. Surface B can be selected by clicking an “ACCEPT” button 202 in the operation window 200. This is followed by execution of the processing of steps S108 to S110 in a manner similar to that of the example of the prior art described above. Thus, a surface selection operation is performed and dimensions are input to the 3D model.
The case illustrated above is such that when two operations for inputting distance dimensions are performed, surface A, which is being displayed in the first surface selection, and surface B, which is not being displayed in the second surface selection, are selected. However, the order may be reversed as a matter of course. That is, surface B, which is not being displayed in the first surface selection, and surface A, which is being displayed in the second surface selection, may be selected. In this case, if the surface to be selected is not being displayed at step S102, it is so arranged that the surface to be selected is displayed using the operation window 200 in a manner similar to that of steps S107A to S107D (steps S104A to S104D). Further, if the surface to be selected is being displayed at step S105, then the processing of step S106 is executed in a manner similar to that of step S103. With 3D-CAD, such an operation for selecting surfaces is essential in various operations.
However, the two surface selecting methods of the prior art described above involve many procedural steps for the purpose of selecting a desired surface. That is, with the former method, it is necessary to change the attitude of the 3D model so as to display a desired surface in order that the surface may be clicked. With the latter method, it is necessary to establish the surface selection mode by performing a prescribed operation and then highlight the desired surface.
Generally, a 3D-CAD operator, such as a product designer, must create attribute information such as several hundred to several thousand dimensions in a situation where the 3D model is complex. Consequently, repeating the above-described procedures whenever a surface is selected increases the burden upon the product designer, increases the number of man-hours involved in the product design process and, as a result, increases the number of man-hours for the overall component fabrication and lengthens the time needed for fabrication of the component. This means that if the above-described procedures could be dispensed with in the operation for selecting surfaces, the efficiency of the attribute-information input operation would be improved significantly.